Here is the full text of Conservative leader David Cameron's speech on his party's policy towards the European Union:
Yesterday in Prague, the Czech Constitutional Court rejected the one remaining challenge to the Lisbon Treaty, and the President of the Czech Republic signed it.
The Lisbon Treaty has now been ratified by every one of the twenty seven member states of the European Union, and our campaign for a referendum on the Lisbon Treaty is therefore over.
Why? Because it is no longer a Treaty: it is being incorporated into the law of the European Union.
Next week, the new posts that the Lisbon Treaty creates - a President and a Foreign Minister - will be filled.
We cannot hold a referendum and magically make those posts - or the Lisbon Treaty itself - disappear, any more than we could hold a referendum to stop the sun rising in the morning.
I know, from the many public meetings I've held around the country, from the huge number of letters and emails that I receive, how much the people of this country will resent the fact that we cannot now have the referendum we were promised.
The decision to promise, and then deny, a referendum was taken by Tony Blair and Gordon Brown.
The betrayal was backed and matched by the Liberal Democrats.
And I believe it ranks alongside the expenses scandal as one of the reasons that trust in politics has broken down.
Of course I wanted a referendum on the Lisbon Treaty.
I've argued for it, campaigned for it, put it front and centre in our European election campaign.
We have voted for it in Parliament.
I've challenged the Prime Minister about his broken promise at every opportunity.
And if the Treaty had not been ratified by every European government when we came to the election, we would have held a referendum on it.
But now it has been ratified.
And I always said that if this happened, I would set out immediately how a Conservative Government would respond.
So today, I want to speak directly to the British people.
I want to explain what a new Conservative government will do to protect Britain's interests in Europe and salvage something from the mess that Labour will have left us.
And I want to speak to our European partners too, to set out clearly what they can expect from a Conservative government in Britain.
First, we will make sure that this never happens again.
Never again should it be possible for a British government to transfer power to the EU without the say of the British people.
If we win the next election, we will amend the European Communities Act 1972 to prohibit, by law, the transfer of power to the EU without a referendum.
And that will cover not just any future treaties like Lisbon, but any future attempt to take Britain into the euro.
We will give the British people a referendum lock to which only they should hold the key - a commitment very similar to that in Ireland.
This is a major constitutional development.
But I believe it is now the only way to reassure the British people that powers cannot be given away without their explicit approval in a referendum.
It is not politicians' power to give away - it belongs to the people.
So at the General Election, we will challenge the other political parties to accept the referendum lock and pledge never to reverse it.
NO MADE-UP REFERENDUM
I recognise there are some who, now that we cannot have a referendum on the Lisbon Treaty, want a referendum on something else...anything else.
But I just don't think it's right to concoct some new pretext for a referendum simply to have one for the sake of it.
That wouldn't survive serious scrutiny.
I don't think a made-up referendum will get Britain anywhere.
For instance, what about a referendum asking for a mandate for our negotiating aims in Europe?
We would have just asked for that mandate in an election and received it.
Would we really want to turn round straight after an election, with the public finances in the state they are in and the economy as fragile as it is and ask the same question all over again?
A made-up referendum might make people feel better for five minutes but my job is to put together a plan that lasts five years, and I don't think a phoney referendum should play any part in that.
Let me repeat: a Conservative government will guarantee a referendum if there is any attempt to transfer further powers from Britain to the EU.
But if we wasted everyone's time and taxpayers' money on a referendum that has no practical effect, I don't think the British people would thank us for it.
In any case, there is more we can do than simply promise a referendum lock on any future handover of power.
Take the sovereignty of our laws.
Because we have no written constitution, unlike many other EU countries, we have no explicit legal guarantee that the last word on our laws stays in Britain.
There is therefore a danger that, over time, our courts might come to regard ultimate authority as resting with the EU.
So as well as making sure that further power cannot be handed to the EU without a referendum, we will also introduce a new law, in the form of a United Kingdom Sovereignty Bill, to make it clear that ultimate authority stays in this country, in our Parliament.
This is not about Westminster striking down individual items of EU legislation.
It is about an assurance that the final word on our laws is here in Britain.
It would simply put Britain on a par with Germany, where the German Constitutional Court has consistently upheld - including most recently on the Lisbon treaty - that ultimate authority lies with the bodies established by the German Constitution.
But people will rightly say that the Lisbon Treaty does not just transfer powers to Brussels today.
It allows further powers to be transferred in the future, because it contains a mechanism to abolish vetoes and transfer power without the need for a new Treaty.
We do not believe that any of these so-called ratchet clauses should be used to hand over more powers from Britain to the EU.
Furthermore, we would change the law so that any use of a ratchet clause by a future government would require full approval by Parliament.
These changes: the referendum lock, the Sovereignty Bill, stopping the use of ratchet clauses, all these changes can be put in place by our own Parliament.
They do not require the approval of our European partners - merely the sanction of the British people at the ballot box, which we will seek at the forthcoming General Election.
They will put in place real protection for our democracy - protections other countries have but which are missing here in Britain.
They would increase accountability, and they would ensure that the breach of trust committed by this Labour Government could never happen again.
Those two words - never again - will be on our leaflets, in our Manifesto: we will make sure that the British people remember who it was that broke their promise - Labour, and who it is that will stop this happening again - the Conservatives.
But these measures are all about preventing problems in the future.
They don't deal with the problems we are facing today, which will now be made worse by the ratification of the Lisbon Treaty.
In essence, these problems boil down to the steady and unaccountable intrusion of the European Union into almost every aspect of our lives.
A Conservative Government will address some of these problems by negotiating three specific guarantees with our European partners guarantees over powers that we believe should reside with Britain, not the EU.
First, social and employment legislation.
Of course, Britain used to have an opt-out from the Social Chapter: but Labour foolishly gave this up.
And today, too much EU legislation in this area is damaging both our economy and our public services.
So we will want to negotiate the return of Britain's opt-out from social and employment legislation in those areas which have proved most damaging to our economy and public services for example the aspects of the Working Time Directive which are causing real problems in the NHS and the Fire Service.
The second British guarantee we will negotiate is over the Charter of Fundamental Rights.
We must be absolutely sure that this cannot be used by EU judges to re-interpret EU law affecting the UK.
Tony Blair claimed that his Government obtained an opt-out from the Charter.
But what he got - as the Government have now admitted - was simply a clarification of how it works in Britain.
We will want a complete opt-out from the Charter of Fundamental Rights.
The third area where we will negotiate for a return of powers is criminal justice.
We must be sure that the measures included in the Lisbon Treaty will not bring creeping control over our criminal justice system by EU judges.
We will want to prevent EU judges gaining steadily greater control over our criminal justice system by negotiating an arrangement which would protect it.
That will mean limiting the European Court of Justice's jurisdiction over criminal law to its pre-Lisbon level, and ensuring that only British authorities can initiate criminal investigations in Britain.
I recognise, of course, that taking back power in these areas, or negotiating arrangements that suit the UK, is not something we can do unilaterally.
It means changing the rules of an institution of which we are a member - changing rules that Britain has signed up to.
If we want to make changes, we will need to do that through negotiation with our European partners, and we will need the agreement of all twenty seven member states.
I also recognise that these are highly complex areas, where we need to think through the practical details with great care.
William Hague is now leading detailed work to examine precisely what we will need to change, and, if we win the next election, his work will draw on the specialised legal advice which the Government has available to it, as well as the expertise of officials from the Foreign Office and other relevant departments.
But success in these negotiations will establish an extremely important principle: that European integration is not a one way street and that powers can be returned from the EU to its member countries, a principle that was envisaged in the Laeken Declaration nearly a decade ago.
Let me be clear. Our guarantees are essential, realistic and deliverable.
Essential, because we have identified the areas of the Lisbon Treaty that cause the deepest concern, and the ones with greatest potential to interfere with our democracy.
Realistic, because we will propose that these British guarantees are added as protocols to a future accession treaty - like the recently concluded Irish guarantees.
And deliverable, because we have chosen areas where the return of powers from the EU to Britain protects our distinctive national interests without harming the interests of our European partners.
THE NEXT PARLIAMENT
So, yes, I believe we will be able to negotiate the return of the powers I have set out.
But no, we will not rush into some massive Euro-bust-up.
We will take our time, negotiate firmly, patiently and respectfully, and aim to achieve the return of the powers I have set out over the lifetime of a parliament.
I know some people will want me to go further, and faster. To them let me say this:
If we win the election, we will inherit the worst public finances of any incoming government for fifty years.
We will have a generational challenge to get Britain to live within her means, to secure economic recovery and to deliver this country from the appalling mess left by this Labour Government.
That has to come before anything else.
THE LONGER TERM
These steps: a referendum lock to prevent this ever happening again, and the return of a specific set of powers. I believe these things can stop Britain's relationship with the EU from heading in the wrong direction.
Clearly we will be asked the question: what if you cannot get these guarantees and what if Europe continues to head in the wrong, centralising direction? Let me answer that question in advance.
Well, if that were to happen, then of course we can return to this subject in a manifesto for the parliament after the next one.
Let me be clear: this is not something we want to happen. Nor is it something we expect to happen.
But if those circumstances were to occur, we would not rule out a referendum on a wider package of guarantees to protect our democratic decision-making, while remaining, of course, a member of the European Union.
But that would be a judgement for the future, not for this election or for the next Parliament.
What I have set out today settles our policy for the next parliament.
I just want to conclude by saying something clearly to our European partners.
My purpose in committing any government I lead to these measures is not to frustrate or to sabotage the operation of the European Union.
It is to put Britain's role in the EU on a more positive footing.
As we commemorate the twentieth anniversary of the fall of the Berlin Wall, we should remember that the European Union has done much to reconcile the painful division of Europe and to spread democracy and the rule of law across our continent.
But it should not rest on those achievements.
Today, European countries need to work together to combat global climate change, to fight global poverty, to boost global economic growth.
If I am elected Prime Minister, the British Government I lead will be an active member of the European Union.
On energy security, on climate change, on growth, on global poverty, we will look forward to working with our European partners to make progress on those issues.
We will press to keep the doors of the European Union open to new member states, especially to entrench stability in the Western Balkans where so much European blood has flowed, and also to Turkey.
We will stand for open markets, and a strong transatlantic relationship; an EU that looks out to the world, and that builds strong and open relations with rising powers like China and India.
We will want to see a tough financial settlement in the forthcoming negotiations on the EU budget, ensuring that Britain does not pay more than its fair share.
We will pay particular attention to the area of financial regulation, where we will be vigilant and tenacious in defending the competitiveness of the City of London.
Like every other Member State, we will fight our corner to advance our national interests.
But our guiding principles will be these: we believe Britain's interests are best served by membership of a European Union that is an association of its member states, we will never allow Britain to slide into a federal Europe and that means we will watch closely how the Lisbon Treaty works out in practice.
We will put in place a referendum lock, so never again can a British government transfer powers to the EU without the people giving their consent in a referendum.
We will enact a United Kingdom Sovereignty Bill, making clear that ultimate authority rests with our Parliament.
And we will negotiate for a specific set of British guarantees that are realistic, deliverable - and essential.
That is our programme for Government.
That is the mandate we will seek at the next election.
In this area - Britain's relationship with Europe - what people want from their politicians is some straight talk and plain speaking.
They were told we were joining a Common Market and it turned out to be a European Union.
They were told they would have a say over the European constitution but that promise was broken.
People are fed up with the endless lies and spin, they just want to know what we can achieve and how.
That is what I will deliver.
I said we would leave the federalist group in the European Parliament and we did.
I said we would have a referendum on the Lisbon Treaty and if it hadn't been ratified we would have had that referendum.
But I did not promise a referendum come what may because once the Lisbon Treaty is the law, there's nothing anyone can do about it and I'm not going to treat people like fools and offer a referendum that has no effect.
What I am promising today is doable, credible, deliverable.
That's what this is all about.
Giving the British people a policy on Europe that they can actually believe in.